1. Field of the Invention
The present invention relates to a data storage cartridge suitable for use as a back-up memory for storing data in a high recording density in, for example, a CPU (central processing unit).
2. Description of the Related Art
A data storage cartridge serving as a back-up memory for storing data in a high recording density in a CPU is disclosed in Japanese Patent Publication (Kokoku) No. 52-14976.
As shown in FIGS. 5 to 9, a data storage cartridge of this kind has a cartridge case 1 formed by fastening a case body 3. i.e., an upper half case, formed of a transparent synthetic resin in the shape of a shallow box to a base plate 2, i.e., a lower half case, formed of aluminum or a synthetic resin in the shape of a flat plate with screws. A pair of tape reels 4 having each a pair of flanges 4a and 4b and formed of a synthetic resin, such as a PC resin, are supported for rotation on the base plate 2, and a magnetic tape 5 is held on the pair of tape reels 4 so as to extend between the pair of tape reels 4.
The magnetic tape 5 is guided by three flanged tape guides 6 so as to extend along the inner surface of the front wall 3a of the case body 3. A driving roller 7 formed of a synthetic resin is supported for rotation on the base plate 2 substantially at the middle of the front side of the base plate 2, and a pair of guide rollers 8 are supported for rotation on the base plate 2 in the opposite rear corners of the base plate 2. An elastic driving belt 9, such as a rubber belt, is wound tautly around the driving roller 7 and the pair of guide rollers 8 so as to extend along a substantially T-shaped path. Driving portions 9a of the driving belt 9, extending between the driving roller 7 and the guide rollers 8 are in pressure-contact with the circumferences of the coils 5a of the magnetic tape 5 wound on the tape reels 4, respectively.
The pair of tape reels 4, the driving roller 7 and the pair of guide rollers 8 are supported for rotation respectively on support shafts 10 of a metal or the like fixedly set in an upright position on the base plate 2 by press-fitting or the like and closely received in the center holes 11 of the tape reels 4, the driving roller 7 and the guide rollers 8. A mirror 12 for the optical detection of the tape ends of the magnetic tape 5 is disposed behind the front portion of a tape path along which the magnetic tape 5 travels.
The upper flange 4a of each tape reel 4 is provided integrally and coaxially with a pivot 4c on the upper surface thereof. The lower flange 4b of each tape reel 4 is provided integrally and coaxially with a hub 4d on the upper surface thereof, and the hub 4d is provided integrally and coaxially with a cylindrical boss 4e. The driving roller 7 and the guide rollers 8 are formed of a POM resin or the like and have crowned working surfaces 7a and 8a for stabilizing the driving belt 9 thereon, respectively. The driving roller 7 is provided integrally with an upper flange 7b at its upper end, and cylindrical bosses 7c respectively on its upper and lower ends. Each guide roller 8 is provided integrally with bosses 8b respectively on its upper and lower ends. Each tape guide 6 is provided integrally with an upper flange 6a and a lower flange 6b to maintain the magnetic tape 5 on a fixed level.
The magnetic tape 5 is wound on the hub 4d of each tape reel 4 between the upper flange 4a and the lower flange 4b. The magnetic tape 5 travels along the barrel between an upper flange 6a and a lower flange 6b of each of the three tape guides 6. The driving belt 9 is wound round the respective crowned working surfaces 7a and 8a of the driving roller 7 and the guide rollers 8. Thus, the magnetic tape 5 and the driving belt 9 are extended with their center lines included in a plane P.sub.1.
The opposite side walls 3b of the case body 3 are recessed slightly to form a pair of parallel side grooves 13. Front portions of the opposite side edges 2a of the base plate 2 are recessed to form positioning recesses 14.
Referring to FIG. 5, when the data cartridge is inserted in a recording/reproducing apparatus, a lid 18 disposed between the base plate 2 and the case body 3 so as to cover a recess 17 formed in the front edges of the base plate 2 and the case body 3 on one side of the driving roller 7 is turned in the direction of the arrow a, and then a magnetic head 19 included in the recording/reproducing apparatus is advanced in the direction of the arrow b into the recess 17 so as to come into contact with the magnetic tape 5. At the same time, a motor, not shown, included in the recording/reproducing apparatus is actuated to advance a friction roller 21, such as a rubber roller, in the direction of the arrow c through an opening 20 formed in the front wall 3a of the case body 3 at a position corresponding to the driving roller 7 so that the friction roller 21 is pressed against the upper flange 7b of the driving roller 7. Then, the friction roller 21 drives the driving roller 7 for rotation in the direction of the arrow d to turn the driving belt 9 in the direction of the arrow e and, consequently, the driving portions 9a of the driving belt 9 in contact with the coils 5a of the magnetic tape 5 drive the tape reels 4 for rotation in the direction of the arrow e. Consequently, the magnetic tape 5 travels in the direction of the arrow f at a high speed in the range of 25 to 120 in./sec, while data provided by the CPU is recorded on or recorded data is reproduced from the magnetic tape 5 with the magnetic head 15.
As shown in FIGS. 8 and 9, the pivots 4c of the tape reels 4 are pressed against the lower surface 3d of the upper wall 3c of the case body 3 by the resilience of the upper flanges 4a so that the lower end of the bosses 4e of the tape reels 4 are pressed against the upper surface 2b of the base plate 2. The extremities of the pivots 4c are fitted respectively in positioning holes defined by cylindrical projections 23 formed integrally with the upper wall 3c of the case body 3. Three cylindrical projections 24 formed on the lower surface of the upper wall 3c of the case body 3 integrally with the upper wall 3c are in contact with the upper ends of the respective upper bosses 7c and 8b of the driving roller 7 and the guide rollers 8 to hold the lower ends of the respective lower bosses 7c and 8b of the driving roller 7 and the guide rollers 8 in contact with the upper surface 2b of the base plate 2.
Since the tape reels 4, the driving roller and the two guide rollers 8 are thus biased toward the base plate 2 in the cartridge case 1, the thickness H of the internal space of the cartridge case 1 is not utilized effectively, and the distance A.sub.1 (FIG. 8) between the lower surface of the upper flange 4a of each tape reel 4 and the upper surface of the base plate 2, which limits the width W.sub.1 of the magnetic tape 5, and the distance A.sub.2 between the lower surface of the flange 7b of the driving roller 7 and the upper surface of the base plate 2 are limited to comparatively small values. Therefore, it has been impossible to use the cartridge case 1 thus constructed for containing a magnetic tape having a width greater than 1/4 in. and the magnetic tape 5 of only 1/4 in. in width W.sub.1 has a comparatively small recording capacity.
Incidentally, data cartridges of this kind are classified as either standard S-type data cartridges, i.e., data cartridges having a smaller standard size, or as standard L-type data cartridges, i.e., data cartridges having a larger standard size, and both the standard S-type data cartridges and the standard L-type data cartridges are designed for magnetic tapes of 1/4 in. in width.
The dimensions X, Y and Z indicated in FIG. 7 of the standard data cartridges are standardized. For S-type data cartridges, X=80.98 mm, Y=61.11 mm and Z=14.73 mm, and for L-type data cartridges, X=152.4 mm, Y=101.6 mm and Z=17.15 mm.
The inventors of the present invention intended to enable the cartridge case 1 to contain a magnetic tape having a width greater than the width W.sub.1 of the magnetic tape 5 and a recording capacity greater than the magnetic tape 5 without changing the dimension Z of the cartridge case 1, by utilizing a space of a thickness H.sub.0 (FIG. 8) extending between the lower surface 3d of the upper wall 3c of the case body 3 and the upper edge 5b of the magnetic tape 5 for containing an upper portion of a magnetic tape having a width greater than the width W.sub.1 of the magnetic tape 5.
When a magnetic tape having a width greater than the width W.sub.1 of the magnetic tape 5 is contained in the cartridge case 1, the plane P.sub.1 including the respective center lines of the magnetic tape and the driving belt 9 must be shifted toward the upper wall 3c of the case body 3, and the center lines of the crowned working surfaces 7a and 8a of the driving roller 7 and the guide rollers 8 must be shifted accordingly toward the upper wall 3c of the case body 3.
Accordingly, the driving roller 7 and the guide rollers 8 for a data cartridge for containing a magnetic tape of one specific width and those for a data cartridge for containing a magnetic tape of another specific width differ from each other in dimensions and, consequently, a driving roller 7 and guide rollers 8 of certain dimensions cannot be commonly used for those cartridge cases for containing magnetic tapes having different widths, respectively, which has been a first problem to be solved.
A second problem in the known data cartridges containing a magnetic tape of 1/4 in. width has been that the magnetic tape of 1/4 in. in width has a comparatively small recording capacity.